Epidemiological Interpretation of a Journal article

I am reading a journal article (similar to one that will be on my final) that deals with air pollution and I am trying to epidemiologically interpret the data and see if it makes sense. I would appreciate some professional opinions on this article. Particularly, how would "you" the professional answer the following questions?

1.) what type of study is it;
Observational- Descriptive or
Analytical (cross-sectional, case control, cohort) or

Experimental- (RCT, Field trial, or community trial).

2.) the strengths and weaknesses of the article.

3.) Did the authors interpret their data correctly or are they extrapolating far too much?

4.) Are the results relevant, and applicable?

5.) Is the paper valid, and reliable?

6.) Is there evidence for a causal relationship?

Basically evaluating the quality of the study using epidemiology techniques. Is there sufficient evidence to warrant a public health intervention?